Does knowledge of being a carrier of the pathological Huntington disease mutation trigger onset of the disease, influence self-awareness and allow carriers to identify symptoms of disease onset? These are questions raised by persons who requested presymptomatic testing and we went back to 75 of them. We showed that having motor signs on examination did not correlate with subjective recognition of them. In carriers without motor signs, self-observation was high despite the lack of objective signs. The view of carriers was not always concordant with the medically defined onset, highlighting difficulties for its use as an outcome in future trials. (By Dr. Alexandra Durr, http://jmg.bmj.com/content/early/2017/01/12/jmedgenet-2016-104199 )